Recent estimates suggest that the number of U.S. men with erectile dysfunction may be near 10-20 million, and inclusion of individuals with partial erectile dysfunction increases the estimate to about 30 million. Electrical stimulation can be used to treat erectile dysfunction. The targets of electrical stimulation are the cavernous nerves. The cavernous nerves run bilaterally between the prostate and the rectum as they course from the sacral spinal cord to the corpora cavernosa in the penis. Near the rectum, the nerves form more of a plexus than a coherent nerve, and they are interlaced with small arteries and veins as well as fatty tissue. This collection of small nerve fibers, arteries, and veins can be referred to as the neurovascular bundle.
The neurovascular bundle containing the cavernous nerve fibers is exposed during a common procedure to remove the prostate, known as nerve-sparing radical prostatectomy. Following this procedure, approximately half of men are left impotent, and an additional number may not be able to achieve penetration.
The axons are unmyelinated and are very small in diameter which means that the stimulation threshold is relatively high. Also, the neurovascular bundle is adhered to the rectum, and separating it from the rectum may lead to damage of the cavernous nerve.